Manual reset device with indicating means

ABSTRACT

An indicating reset device for moving a safety cutoff switch or valve from its tripped or cutoff position toward which it is biased to an operative set position, the device having a slidably mounted plunger biased in one direction to an indicating position and operative when pushed oppositely to a non-indicating position to move a safety switch or valve to its set position, the device further including means for latching the plunger in its nonindicating position, the latching means being released by the biasing force of the safety switch or valve when an unsafe operating condition causes it to be tripped, and the plunger member having a conspicuously colored end portion which is retracted from view when in a non-indicating position and exposed when released to an indicating position.

United States Patent [191 Becker [75] Inventor: Eilhard J. Becker, St. Louis, Mo. 73] Assignee: Emerson Electric Co., St. Louis, Mo.

[22] Filed: Dec. 7, 1971 [21] Appl. No.: 205,488

52 0.5. CI. ..200/169 PB, 337/62 [51] Int. Cl. ..H0lh 9/20 [58] Field of Search ..200/167 R, 169 PB;

[56] References Cited I UNITED STATES PATENTS 3,538,476 11/1970 Auchapt et al. ..337/66 X 2,824,931 2/1958 Ingwersen ..337/62 3,501,729 3/1970 Brackett, Sr ..337/62 X 3,361,821 1/1968 Clarke ..337/66 UX MANUAL RESET DEVICE WITH INDICATING MEANS 1 June 5,1973

Primary Examiner-Robert K. Schaefer Assistant Examiner-William J. Smith Attorney- -Charles E. Markham 57 ABSTRACT An indicating reset device for moving a safety cutoff switch or valve from its tripped or cutoff position toward which it is biased to an operative set position,

the device having a slidably mounted plunger biased in one direction to an indicating position and operative when pushed oppositely to a non-indicating position to move a safety switch or valve to its set position, the device further including means for latching the plunger in its non-indicating position, the latching means being released by the biasing force of the safety switch or valve when an unsafe operating condition causes it to be tripped, and the plunger member having a conspicuously colored end portion which is retracted from view when in a non-indicating position and exposed when released to an indicating position.

6 Claims, 3 Drawing Figures view;

I FIG. 3 is a view MANUAL RESET DEVICE WITH INDICATING MEANS This invention relates generally to safety cutoff switches or valves which are biased in a cutoff position and are arranged to be moved manually to a set position and retained there so asto complete an electrical circuit or permit the flow of fluid during normal operatingconditions and which include means responsive to an abnormal operating condition to effect the release and return of the switch or valve to its cutoff position. More specifically, the invention relates to means for manually moving a safety cutoff switch or valve to its set position and for indicating its tripped orcutoff position.

The provision of a small incandescent lamp and a control switch therefor to indicate the tripped or cutoff position of aswitch'or valve may be employed when an adequate source of electrical energy is conveniently available. However, in many of the current gas burner control systems or devices, the main burner fuel control valve is directly actuated by a thermostatic device and the safety cutoff valve is retained in its set position by electromagnetic means energized by a thermocouple heated by a pilot burner. The electrical energy supplied by the thermocouple is usually far short of being The upper smaller bore portion l4slidably receives the upper large diameter portion 22 of a plunger member 24. The plunger 24 has a lower smaller diameter portion 6 slidably received in the bore 28 in the retaining and mounting plug 20. An intermediate reduced diameter portion 30 of plunger 24 provides a shoulder 32 A at the point of reduction of bore 38 and within. the

adequate'to heat an indicating lamp filament to incandescence, so that the use of an indicating lamp in these installations involves the cost of wiring from the control device to some other electrical'source.

A dependable, economically constructed, anduniversally adaptable means for resetting and indicating a tripped position of a safety cutoff switch or valve is 1 highly desirable, and it is, therefore, an object of this invention to provide this means.

. A further object is to provide an indicating manual reset device which requires no electrical energy and is universally adaptable to use with safety cutoff switches or valves having a limited biasing force urging them toward their cutoff position.

Further objects and advantages will appear when reading the following complete description of one form of the invention in connection with the accompanying drawing. i

'- In the drawing:

F IG. 1 is a top plan view of an'indicating manual reset device constructed in accordance with the present invention;

' FIG. 2 is a longitudinal cross-sectional view of the device shown mounted'in the'top wall of a safety cutoff switch casing nd in operative association with the switch, the device being in a non-indicating position and the switch being in an operative set position in this similar to that of FIG. 2, except that the reset device is in an indicating position and the switch is in a tripped or cutoff position.

Referring to the drawing in more detail, the reset device comprises a cylindrical member 10 having a stepped bore extending longitudinally therethrough. The bore comprises a larger diameter lower portion 12 and an upper smaller diameter portion 14. A bevelled shoulder 16 is formed at the point of reduction in bore diameter, and a lower end portion of the larger bore portion 12 is screw threaded at 18 and receives a screw threaded mounting and retaining plug 20. The plug 20 has a head 21 and a longitudinal bore 28' extending therethrough.

upper larger diameter portion 22 of the plunger/The larger upper and the lower smaller diameter portions 38 and 40 of the plunger boreslidably receive, respectively, the larger upper and the lower smaller diameter portions 44 and 46 of a rod 48. The rod .48 has a bevelledv shoulder 50, formed at the point of reduction of its diameter, which is adapted to'seat onthe similarly bevelled shoulder 42 in the plunger bore.

-An upper end portion of the plunger bore portion 38- is screw threaded at 52 and receives a screw-threaded closure screw 54. A relatively light spring 56 biased bebevelled shoulder 42 receives a plurality ofsteel balls 60, there being an equal number-of balls in each portion of bore 58 extending radially from opposite sides of rod 48. The balls60 are freely movable in bore 58. The sum of the diameters of the balls 60 on each side of rod 48 is slightly less than the radial dimension between a side of the larger. upper portion 44 of the rod 48 and the wall of bore portion 12 in cylindrical member 10, but is substantially greater than the radial dimension betweena side of rod portion 44 and the wall of smaller bore portion 14. The outermostballs'bo therefore engage bevelledlshoulder 16. in cylindrical member 10 when plunger 24 is in the depressed position, and rod 48 is downwardly seated as shown in FIG. 2. The plunger is thereby latched in this position against the upward bias of spring-34. A

- The sum of the diameters of balls 60 lying on each side of rod 48 is also slightly less than the radial. dimension between a side of the smaller diameter rod portion 46 and the wall of upper bore portion 14. of cylindrical member 10. Therefore, when rod 48 is moved upward in the plunger against the relatively'light spring 56 sufficiently to permit the balls 60 to roll inward to engage the sides of the smaller diameter rod portion 46,: th'e plunger 24 is released and returns-underthebias' of spring 34 to the position shown in FIG. 3. In thein'dicating position shown in FIG. 3, a substantial upper portion of the plunger 24 is exposed to view, while-:in the non-indicating position shownn-in FIG. 2,- the plunger24 is completely retracted in cylindrical memthe device rigidly to the casing wall. The safety cutoff switch 65 comprises a pair of switch arms 66 and 68 fixed at one end and carrying, respectively, at their free ends a movable contact 70 and a stationary contact 72. The switch blades 66 and 68 are arranged transverse to the axis of the reset plunger 24, with the free end of upper blade 66 in substantial alignment with the axis of the plunger. The upper blade 66 is flexible and has a free form, as shown in FIG. 3, in which contacts 70 and 72 are separated; that is, in a circuit breaking or cutoff position.

When the free end of the upper blade 66 is pressed downward, the contacts 70-72 are closed and the switch is in an operative set position, in which position it is arranged to be retained under normal operating conditions by a latch member 74 'carriedon the upper free end of a bimetal blade 76, as shown in FIG. 2. The bimetal blade 76 is anchored at its lower end and, under normal operating conditions, assumes the position shown in FIG. 2. Under conditions of operation which effect the warping of bimetal blade 76, as shown in FIG. 3, the switch blade 66 is released or tripped, whereupon the switch moves to an open or cutoff position by virtue of the resiliency of switch blade 66.

OPERATION When it is desired to move the switch 64 from the tripped position. shown in FIG. 3 to the operative set position shown in FIG. 2, the plunger is manually depressed sufficiently to engage the switch blade 66 and move contacts 70-72 together. If at this time the bimetal blade 74 is in a cool or normal position, the blade 66 will be retained by the latch 74 and the switch will be retained in a closed or set position. When depressing plunger 24 from its FIG. 3 position to close the switch, rod 48 will be moved downward on its seat 42 by the spring 56 when the balls 60 enter the large diameter bore portion 12. When the plunger has moved downward sufficiently for the balls '60 to enter enlarged bore portion 12, they are free to move radially outward and permit the upper enlarged portion 44 of the rod to seat on seat 42. This occurs somewhat before rod 24 is depressed sufflciently to close contacts 70-72.

After the switch is closed and latched by latch 74, the plunger is released and returns upwardly slightly under the bias of spring 34 until the outer balls 60 engage the shoulder 16, thereby holding the plunger in the depressed position of FIG. 2. In closing the switch contacts the plunger is depressed slightly below the upper end of cylindrical member 10, the upper end of bore 14 being flared at 78 to permit this. When released the plunger returns substantially flush with the upper end of member 10. The lower reduced diameter portion 46 of rod 48 is made sufficiently long to project somewhat from the lower end of plunger 24 when the rod is seated on seat 42, as shown in FIG. 2.

An abnormal operating condition which causes the free end of bimetal blade 76 to warp to the left releases switch blade 66 to swing upward to its free position, whereby it engages the projecting lower end of rod 48 and moves it slightly upward. This slight upward movement of rod 48 moves the lower reduced diameter portion of the rod into alignment with balls 60 and permits them to roll inward so that they may enter the upper reduced bore portion 14. The plunger is therefore released and moves to the FIG. 3 position under the urging of spring 34.

The upper enlarged portion 22 of plunger 24 has a conspicuous color, preferably red, contrasting sharply with'the color of the member 10 so as to clearly indi' cate a released position of the reset device and, consequently, a cutoff or open condition of the switch. It will be apparent that the friction to be overcome in moving the rod 48 from itsreleased position of FIG. 3 to its FIG. 2 set position is substantially nil, so that the spring 56 biasing the rod to a set position may be made very light. Also, the plunger return spring 34 need only be sufficiently strong to dependably return the plunger upward. The friction to be overcome in releasing the device may, therefore, be very small so that the force i'equired by the switch blade 66.to release the device is quite small.

In other adaptations of the reset device, the closing bias of the control member is usually considerably greater than that provided by the resiliency of a simple flexible switch blade. Also, in safetycutoff devices in which the control memberv includes means to effect its snap action movement between on and off positions, the carryover of the snap acting mechanism after it is moved to a critical point by theplunger 48 provides space for the rod 48 to project slightly below the lower end of the plunger 24. The slight overtravel of plunger 24 in resetting the control is therefore unnecessary in this use of thedevice.

I claim:

1. An indicating manual reset device comprising an elongated support member having an axial bore therethrough, a plunger longer than said support member axially slidable therein, means biasing said plunger in one direction to an indicating position wherein one end portion thereof projects from one end of said support member, stop means limiting plunger movement in said one direction, the other-end of said plunger projects from the other end of said support member and is adapted to engage and move a-control device from a biased released position to a set position when said one end portion thereof is manually depressed to a nonindicating position substantially flush with said one end of said support member, latch means operative to retain said plunger in said non-indicating position when it is moved there, said latch means including a rod member axially slidable in said plunger, said rod member being axially biased in a'latching position wherein an end portion thereof projects beyond said other end of said plunger, and said latch means being tripped when said rod member is moved axially inward a short distance from said projected position.

l 2. The device claimedin claim 1 in which said latch means further includes radially movable elements moved radially by said rod member to latching positions between opposing surfaces on said support member and said plunger when said rod member is moved to a latching position, thereby to preclude their relative movement.

3. The device claimed in claim 2 inv which said rod member includes an axially inclined surface engaging said radially movable elements and in which said opposing surface on said support member is axially inclined.

4. The device claimed in claim 3 in which said opposing surface on said support member comprises a bevelled annular shoulder formed in its axial bore and in which said elements are slidable in a transverse bore through said plunger. 1

. wall of said support member.

5. The device claimed in claim 4 in which said elements comprise a plurality of balls in said transverse bore in said plunger between said operating rod and the 6. The device claimed in claim 1 in which said elongatedsupport member is of hollow cylindi'ical form, is

provided with an internal screw-threaded end portion,

smaller diameter other end of said plunger. 

1. An indicating manual reset device comprising an elongated support member having an axial bore therethrough, a plunger longer than said support member axially slidable therein, means biasing said plunger in one direction to an indicating position wherein one end portion thereof projects from one end of said support member, stop means limiting plunger movement in said one direction, the other end of said plunger projects from the other end of said support member and is adapted to engage and move a control device from a biased released position to a set position when said one end portion thereof is manually depressed to a nonindicating position substantially flush with said one end of said support member, latch means operative to retain said plunger in said non-indicating position when it is moved there, said latch means including a rod member axially slidable in said plunger, said rod member being axially biased in a latching position wherein an end portion thereof projects beyond said other end of said plunger, and said latch means being tripped when said rod member is moved axially inward a short distance from said projected position.
 2. The device claimed in claim 1 in which said latch means further includes radially movable elements moved radially by said rod member to latching positions between opposing surfaces on said support member and said plunger when said rod member is moved to a latching position, thereby to preclude their relative movement.
 3. The device claimed in claim 2 in which said rod member includes an axially inclined surface engaging said radially movable elements and in which said opposing surface on said support member is axially inclined.
 4. The device claimed in claim 3 in which said opposing surface on said support member comprises a bevelled annular shoulder formed in its axial bore and in which said elements are slidable in a transverse bore through said plunger.
 5. The device claimed in claim 4 in which said elements comprise a plurality of balls in said transverse bore in said plunger between said operating rod and the wall of said support member.
 6. The device claimed in claim 1 in which said elongated support member is of hollow cylindrical form, is provided with an internal screw-threaded end portion, and includes a centrally perforated and headed screw-threaded plug, which plug provides means for mounting the device in a perforated casing wall, retains said plunger member therein, and slidably guides said smaller diameter other end of said plunger. 